Only one in 30 primary schools gives all seven to 11-year-olds weekly foreign language lessons, research shows.
Fewer than half offer pupils any lessons in subjects such as French, Spanish and German and only a third do so within the school day, the study, published by the Department for Education and Skills, found.
The report sets out the scale of the challenge facing schools to meet the Government's promise that by 2010, every child will be taught a modern foreign language within the school day during key stage 2.
Even those primaries teaching a language reported a lack of certainty about the subject's future. Two-fifths said provision was vulnerable to changes in circumstance.
The study said ministers needed to provide additional resources and training for teachers and ensure schools have sufficient curriculum time, if languages are to flourish.
"The substantial funding implications of delivering the primary modern foreign language entitlement should not be underestimated." Pupils need at least one half-hour session each week plus daily exposure during other lessons if they are to build competence in another language, it added.
Terry Lamb, past president of the Association for Language Learning, said the study showed that provision had improved.
But he said: "We must make sure that all children, no matter where they live, have an entitlement to high-quality language teaching.
"I talk to headteachers who are committed to this, but who ask where the money is to provide it."
The DfES said almost half of primary schools teach pupils foreign languages, up from 20 per cent in 2000. The report is based on questionnaires completed by more than 3,000 schools, 2,825 primary teachers and 113 councils in England.
Language provision varies greatly by region, it found.
Only two councils, which were not named, said that more than 80 per cent of their schools currently offer modern foreign languages.
By contrast, a third of authorities said that fewer than one in five of their primaries did so. French is by far the most commonly taught language.
A third of teachers not teaching languages said they would be keen to do so but many are discouraged by a lack of skills and knowledge.
Only 8.5 per cent described themselves as fluent or fairly fluent in a language and only about a quarter have a GCSE or equivalent qualification.
The provision of foreign language learning for pupils at key stage 2 by Dr Patricia Driscoll, Christ Church university college Canterbury, Dr Jane Jones, King's college London and Dr Gee Macrory, Manchester Metropolitan university is available from www.dfes.gov.ukresearch